Obesity Greatly Raises Endometrial Cancer Risk

Odds are 22 times higher for very overweight women, study finds

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MONDAY, June 22, 2009 (HealthDay News) -- Obesity is already linked to heart disease, diabetes and high blood pressure, but new research finds those extra pounds can also significantly increase a woman's risk of developing endometrial cancer, especially if she experiences early menopause.

Published in the July issue of Obstetrics & Gynecology, the study found that women with a body-mass index (BMI) greater than 35 who were under 45 at the time of their last menstrual period had a 22 times higher risk of developing endometrial cancers than their normal-weight peers.

"In this young population, the risk of endometrial cancer increased dramatically if they had a BMI greater than 25," said study author Cheryll C. Thomas, an epidemiologist at the U.S. Centers for Disease Control and Prevention.

Body-mass index is a measurement used to estimate one's body fat. A BMI between 18.5 and 24.9 is considered normal, according to the CDC. Twenty-five to 29.9 is overweight, and anything 30 or over is considered obese.

Although obesity is a known risk factor for endometrial cancer in pre-menopausal and postmenopausal women, little research has focused on younger women, according to background information in the current study.

Thomas and her colleagues reviewed data from the CDC's Cancer and Steroid Hormone Study, a multi-center, population-based study done in the 1980s. They found 421 women between the ages of 20 and 54 who had been diagnosed with endometrial cancer, and they also recruited a randomly selected control group of 3,159 women from the same areas of the country.

Women who were younger than 45 when they had their last period and had a BMI above 35 had a 21.7 times greater risk of developing endometrial cancer than a woman of normal weight. In women older than 45 at their last menstrual period, those with BMIs above 35 had 3.7 times greater odds of developing endometrial cancer than their normal-weight peers.

Women who had BMIs of at least 25 who were also under 45 at the age of their last menstrual period had about a sixfold increase in risk vs. their normal-weight counterparts.

The researchers suspect that a hormonal imbalance, specifically a lack of progesterone, is likely to blame for the increased risk, Thomas said.

Dr. Diane Yamada, section chief for gynecologic oncology at the University of Chicago Medical Center, said she suspects the "unopposed estrogen" causes the increased risk. Fat tissue, she explained, plays a role in producing estrogen. "People think about estrogen as only coming from the ovaries, but if you have a lot of adipose tissue, you'll have more estrogen."

Whatever the cause, Thomas said these findings highlight the importance of maintaining a healthy weight.

Both doctors said that weight loss can help reduce the risk of endometrial cancer.

"People have to be very aware that obesity not only puts you at risk for heart disease, diabetes, high blood pressure, but also for cancer," said Yamada. "Endometrial cancer is just one of multiple reasons to try to get healthier."

Any woman, overweight or not, who experiences significant changes in her menstrual periods -- such as a period that lasts longer or a heavier flow than usual -- should discuss these changes with her doctor. And, Yamada advised that any postmenopausal woman who develops bleeding should call her doctor right away, because these could be signs of cancer.